210 lines
7.2 KiB
C
210 lines
7.2 KiB
C
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// _____________
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// _________________
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// _____/~\___________/\_
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// ______/\_/\_________/\____
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// ______/\___/\_______/\______
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// _____/\_____/\_____/\_______
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// ____/\_______/\___/\________
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// __/\_________/\_/\________
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// /\___________/~\_______
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// ___________________
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// _____________
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//
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//***************************************************************************//
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//* *//
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//* Project : Neural Surround *//
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//* File : FFT_Overlapped_Stereo.c *//
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//* Description : A windowed and overlapped FFT and IFFT *//
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//* Author(s) : Jeff Thompson *//
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//* *//
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//* Copyright (c) Neural Audio Corp. 2008 *//
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//* *//
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//***************************************************************************//
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#include "Neural_THX_Encoders.h"
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#include <stdlib.h>
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#include <math.h>
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//***************************************************************************//
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//* FFT_Overlapped_Stereo_INIT(...) *//
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//***************************************************************************//
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int FFT_Overlapped_Stereo_INIT(FFT_Overlapped_Stereo_Struct * pPersistent,
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float * pTempBuffer0, //Size must be 2*Framesize
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float * pTempBuffer1, //Size must be 2*Framesize
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unsigned int Framesize)
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{
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int n, j;
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size_t memNeeded;
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if(Framesize != HALFFFTSIZE) return UNSUPPORTED_FRAMESIZE;
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pPersistent->pSineWin = (float*)GetSineWindow();
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pPersistent->pReal = pTempBuffer0;
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pPersistent->pImag = pTempBuffer1;
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for(n = 0; n < HALFFFTSIZE; n++){
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pPersistent->pOverlappedBuffer0[n] = 0;
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pPersistent->pOverlappedBuffer1[n] = 0;
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}
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// Let's do something that will speed everything up
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memNeeded = FFT_MEM_CHUNK;
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pPersistent->state = THX_kiss_fft_alloc(FFTSIZE,0,fft_buff,&memNeeded);
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// Lets make some memory for our buffers
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for(j = 0; j < FFTSIZE; j++)
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{
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pPersistent->pIn[j].r = 0.0f;
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pPersistent->pIn[j].i = 0.0f;
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pPersistent->pOut[j].r = 0.0f;
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pPersistent->pOut[j].i = 0.0f;
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}
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return NRLSUR_OK;
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}
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//***************************************************************************//
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//* FFT_Overlapped_Stereo(...) *//
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//***************************************************************************//
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int FFT_Overlapped_Stereo(float * PtrIn0,
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float * PtrOutReal0,
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float * PtrOutImag0,
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float * PtrIn1,
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float * PtrOutReal1,
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float * PtrOutImag1,
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unsigned int Framesize,
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FFT_Overlapped_Stereo_Struct * pPersistent)
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{
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unsigned int n;
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float Win;
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if(Framesize != HALFFFTSIZE) return UNSUPPORTED_FRAMESIZE;
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// Put input0 values into every even index as "real" data and input1 values into every odd index as "imag" data
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for(n = 0; n < HALFFFTSIZE; n++){
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Win = pPersistent->pSineWin[n];
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pPersistent->pIn[n ].r = Win * pPersistent->pOverlappedBuffer0[n];
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pPersistent->pIn[n ].i = Win * pPersistent->pOverlappedBuffer1[n];
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pPersistent->pIn[FFTSIZE-n-1].r = Win * PtrIn0[HALFFFTSIZE-n-1];
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pPersistent->pIn[FFTSIZE-n-1].i = Win * PtrIn1[HALFFFTSIZE-n-1];
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//Store in pOverlappedBuffer for next call
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pPersistent->pOverlappedBuffer0[n] = PtrIn0[n];
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pPersistent->pOverlappedBuffer1[n] = PtrIn1[n];
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}
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// FFT call
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THX_kiss_fft(pPersistent->state,
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pPersistent->pIn,
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pPersistent->pOut);
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// Pull the information out ...
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// Now parse through the complex output to separate the two input signals
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PtrOutReal0[0] = pPersistent->pOut[0].r; //Real value of DC coefficient
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PtrOutImag0[0] = 0;
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PtrOutReal1[0] = pPersistent->pOut[0].i; //Imag value of DC coefficient
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PtrOutImag1[0] = 0;
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for(n = 1; n < HALFFFTSIZE; n++){
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PtrOutReal0[n] = (float)0.5 * ( pPersistent->pOut[n].r + pPersistent->pOut[FFTSIZE-n].r); // Real output
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PtrOutImag0[n] = (float)0.5 * ( pPersistent->pOut[n].i - pPersistent->pOut[FFTSIZE-n].i); // Imag output
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PtrOutReal1[n] = (float)0.5 * ( pPersistent->pOut[n].i + pPersistent->pOut[FFTSIZE-n].i); // Real output
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PtrOutImag1[n] = (float)0.5 * (-pPersistent->pOut[n].r + pPersistent->pOut[FFTSIZE-n].r); // Imag output
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}
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return NRLSUR_OK;
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}
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//***************************************************************************//
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//* IFFT_Overlapped_Stereo_INIT(...) *//
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//***************************************************************************//
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int IFFT_Overlapped_Stereo_INIT(IFFT_Overlapped_Stereo_Struct * pPersistent,
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float * pTempBuffer0, //Size must be 2*Framesize
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float * pTempBuffer1, //Size must be 2*Framesize
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unsigned int Framesize)
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{
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int n, j;
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size_t memNeeded;
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if(Framesize != HALFFFTSIZE) return UNSUPPORTED_FRAMESIZE;
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pPersistent->pSineWin = (float*)GetSineWindow();
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pPersistent->pReal = pTempBuffer0;
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pPersistent->pImag = pTempBuffer1;
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for(n = 0; n < HALFFFTSIZE; n++){
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pPersistent->pOverlappedBuffer0[n] = 0;
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pPersistent->pOverlappedBuffer1[n] = 0;
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}
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// Let's do something that will speed everything up
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memNeeded = FFT_MEM_CHUNK;
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pPersistent->state = THX_kiss_fft_alloc(FFTSIZE,0,fft_buff,&memNeeded);
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// Lets make some memory for our buffers
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for(j = 0; j < FFTSIZE; j++)
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{
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pPersistent->pIn[j].r = 0.0f;
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pPersistent->pIn[j].i = 0.0f;
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pPersistent->pOut[j].r = 0.0f;
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pPersistent->pOut[j].i = 0.0f;
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}
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return NRLSUR_OK;
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}
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//***************************************************************************//
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//* IFFT_Overlapped_Stereo(...) *//
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//***************************************************************************//
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int IFFT_Overlapped_Stereo(float * PtrInReal0,
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float * PtrInImag0,
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float * PtrOut0,
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float * PtrInReal1,
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float * PtrInImag1,
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float * PtrOut1,
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unsigned int Framesize,
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IFFT_Overlapped_Stereo_Struct * pPersistent)
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{
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unsigned int n;
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float Win;
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float coeff;
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if(Framesize != HALFFFTSIZE) return UNSUPPORTED_FRAMESIZE;
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//Sum X1 + j*X2
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for(n = 0; n < HALFFFTSIZE; n++){
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pPersistent->pIn[n].r = PtrInReal0[n] - PtrInImag1[n]; //Real
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pPersistent->pIn[n].i = -(PtrInImag0[n] + PtrInReal1[n]); //Imag
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}
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//Use the input buffers as temporary buffers
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pPersistent->pReal[HALFFFTSIZE] = 0;
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pPersistent->pImag[HALFFFTSIZE] = 0;
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for(n = 0; n < HALFFFTSIZE-1; n++){
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pPersistent->pIn[FFTSIZE-n-1].r = PtrInReal0[n+1] + PtrInImag1[n+1];
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pPersistent->pIn[FFTSIZE-n-1].i = -(-PtrInImag0[n+1] + PtrInReal1[n+1]);
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}
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// FFT call
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THX_kiss_fft(pPersistent->state,
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pPersistent->pIn,
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pPersistent->pOut);
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coeff = (float)FFTSIZE;
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coeff = 1/coeff;
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for(n = 0; n < FFTSIZE; n++)
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{
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pPersistent->pOut[n].i = -coeff * pPersistent->pOut[n].i;
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pPersistent->pOut[n].r = coeff * pPersistent->pOut[n].r;
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}
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for(n = 0; n < HALFFFTSIZE; n++){
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Win = pPersistent->pSineWin[n];
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PtrOut0[n] = Win * pPersistent->pOut[n].r + pPersistent->pOverlappedBuffer0[n]; // Real output
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PtrOut1[n] = Win * pPersistent->pOut[n].i + pPersistent->pOverlappedBuffer1[n]; // Real output
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}
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for(n = 0; n < HALFFFTSIZE; n++){
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Win = pPersistent->pSineWin[n];
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pPersistent->pOverlappedBuffer0[HALFFFTSIZE-n-1] = Win * pPersistent->pOut[FFTSIZE-n-1].r;
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pPersistent->pOverlappedBuffer1[HALFFFTSIZE-n-1] = Win * pPersistent->pOut[FFTSIZE-n-1].i;
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}
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return NRLSUR_OK;
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}
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